def make_album(singer, album, song_num = None):
    if song_num:
        albums = {
            'singer': singer.title(),
            'album': album.title(),
            'Number of songs': song_num
        }
    else:
        albums = {
            'singer': singer.title(),
            'album': album.title()
        }
    return albums

a = make_album('jay chou', 'fantacy')
print(a)

b = make_album('jay chou', 'fantacy', 10)
print(b)